TSV (Through-Silicon-Via) is the latest technology of making vertical breakover between chips, and wafers to realize the interconnection between chips. Different from the IC packaging bonding and the overlay technology employing salient points, TSV could maximize the density of the piling of the chips in the 3D directions, minimize the dimensions and significantly improve the operation speed of the chips and reduce power consumption.
The key element of the TSV electroplating and copper filling technique is that the copper shall be deposited in the height-depth-width ratio microvias without voids and seams During the electro-deposition, if the copper is plated on both sides and the bottom of the channel at the same plating rate, and that is the Conformal plating, seams may be easily formed in the center of the channel. If the plating rate of the upper part of the channel is higher than that of the lower part, there will be holes in the channel. Only if the plating rate at the bottom of the channel is higher than that at the sides of the channel, can the fully filling of the copper in the channel be ensured. This filling method is called super-conformal plating, or Bottom-up filling.
How to use appropriate process control to achieve super-conformal plating is the key for the filling of high aspect ratio microvia filling. Technically, the electroplating performance of high aspect ratio microvias depends on the equipment capacity, pre-treatment conditions, electroplating solutions, size distribution of micro holes, distribution of hole types and plating parameters.